module ula (
    a,
    b,
    sel,
    result
);

input signed [8:0] a;
input signed [8:0] b;
input [0:0] sel;
output signed [8:0] result;
reg signed [8:0] result;



always @(a, sel, b) begin: _ula_process
    if ((sel == 0)) begin
        result <= (a + b);
    end
    else if ((sel == 1)) begin
        result <= (a - b);
    end
    else begin
        $display("Exception(Error - Operation selected not implemented yet!)");
        $finish;
    end
end

endmodule
